Most of the existing electric space heaters or convection heaters comprise a vertical heat-dissipation plate and horizontally positioned heating elements in intimate contact therewith. This contact is achieved in different ways. Most heaters utilize a flat plate that is shaped to form longitudinal cavities suited for insertion of electrically insulated resistors of circular or other cross section. Finned or corrugated sheets are frequently attached to one or both sides of the flat plate in intimate contact therewith, in order to increase the heat exchange surface and to cause increased circulation of air by the so-called funnel effect. Most heaters are, in addition, provided with outer protective panels to prevent people from being injured by the hot surface. The flat plate used is either single and rolled up at its lower end into a tube for receiving the heating element, or it onsists of two sheets closely connected over their entire surfaces, each sheet being provided with pressed-out bulges which, together with corresponding bulges on the other sheet form closed tubular cavities for the heating elements.
The main drawback of the known heaters is the fact that these are assembled from different, separate parts, viz. a vertical flat plate and finned or corrugated sheets attached thereto. Unless connection between these parts is by welding or soldering, heat transfer from the plate to the corrugated sheets is unsatisfactory, and since soldering or welding is expensive and ofter causes warping of the connected parts, it is generally not in use with these heaters. In any case, making a heater of many parts increases the manufacturing costs, while a heater composed of one plate only, with heating elements incorporated in the plate, would necessitate a great length in order to create the required heating surface.
In view of these drawbacks it is the object of the present invention to provide an electric heater having a relatively large heat dissipating surface concentrated over a relatively short overall length of the unit. Another object of the invention is to provide an inexpensive heater assembled from a minimum of separate components, and to simplify manufacturing by using bending and pressing operations only, without the necessity to connect heat dissipating surfaces only, without the necessity to connect heat dissipating surfaces by soldering, welding or bolting. Still another object is to permit manufacture of the main component in endless lengths and to cut it to the length required for a given heat exchange surface.